The invention relates to a machine tool for sloping the tooth flanks of a gear, with two flanks being milled simultaneously, with a rotationally driven workpiece holder and with two rotationally driven tool spindles adjustable relative to the workpiece along their axes, with the angular alignment relative to the workpiece axis being adjustable for each to receive a milling cutter, especially a face milling cutter or a one-tooth fly cutter, with the workpiece optionally being rotationally driven cyclically or continuously, the tool spindles being correspondingly displaceable forward and backward axially in synchronization with the workpiece cycle, or rotating, fixed axially, in synchronization with the continuous workpiece rotation, with the workpiece being advanced in the axial direction and with each tool spindle having a carriage associated therewith, said carriage being displaceable by an axial displacement drive.
A machine tool of the this type under discussion is known from DE 41 34 925 C1, with the tool spindles received by a carriage being moved back and forth by means of an oscillator at a very rapid sequence of 1200 or more strokes per minute, in synchronization with the rotation of the workpiece. Continuous adjustment of the tool spindles in the direction of the workpiece in order to produce the slopes is superimposed on this. Accordingly, two separate movements take place along the tool spindle axes, namely the oscillating movement and the actual advance displacement that makes the design of such a machine tool more expensive. This document shows that the workpiece can also be indexed one division at a time when impact milling operation is desired, which corresponds to cyclic operation. In this case also, the actual tool feed would be superimposed on the oscillating movement of the tool spindle.